1. Field
Aspects of the present disclosure relate generally to wireless communication systems, and at least some aspects pertain more particularly to power consumption reduction in user equipment in wireless communications systems through power adjustment of communication channels.
2. Background
Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks.
As the demand for mobile broadband access continues to increase, research and development continue to advance the UMTS technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.
One such advancement in conventional systems has been the introduction of closed-loop control for downlink transmissions. In these systems, a mobile station receives certain data and control information on downlink transmissions, and transmits one or more uplink channels including feedback signaling relating to the received downlink transmissions. In this type of system, decisions relating to adjustments of the downlink transmissions may be made in accordance with the feedback transmitted on the uplink. These adjustments can include the downlink transmission power, modulation, and encoding, among others, and may further include decisions whether to retransmit downlink data if the feedback indicates that a packet was not decoded properly at the mobile station.
In these systems, the reliability of the uplink transmission including the feedback information can affect downlink performance. That is, if the feedback is incorrectly received or not received at all, then improper adjustments to the downlink may cause problems with downlink performance. For this reason, there is a desire to utilize uplink feedback transmissions in a way that best improves reliability.
However, the transmission of the feedback information on uplink channels consumes some of the resources available to the mobile station for uplink data transmissions. For this reason, there is a countervailing desire to utilize uplink transmissions in a way that is most efficient and consumes the least amount of resources.
As a result, there is a desire to achieve the most effective balance between reliability and efficiency for uplink transmissions of feedback information even in time-varying channel conditions, particularly in a way that accounts for soft handovers and other incidents that might otherwise affect the wireless link.